Here's How Gmail Detected the Child Abuse Photos Inside Gmail

In the time that has passed since then, the Internet giant has built a database full of hashes, also known as photo fingerprints, for various child abuse images. Each one is unique and they’re attached to a certain image, so it doesn’t matter if someone changes the name of the file.

When Google scans the email and its contents while the messages is being sent, received and stored to the cloud, as per the company’s ToS, the system also detects these hashes. The company is then legally obligated to report them to the authorities, who can then obtain warrants and eventually arrest the culprits.